Heavy vehicle driver workload assessment: Task 7b: In-cab text message system and cellular phone use by heavy vehicle drivers in a part-task driving simulator

Hanowski, Richard; Kantowitz, Barry; Tijerina, Louis · 1996 · Crossref

DOI: 10.1037/e461712008-001

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Summary

This study, conducted by the National Highway Traffic Safety Administration (NHTSA) and Battelle Memorial Institute, evaluates the impact of in-cab secondary tasks on heavy vehicle driver workload and performance. Motivated by the increasing integration of Intelligent Transportation Systems (ITS) and communication devices in commercial vehicles, the research aimed to assess the safety implications of using cellular phones and text message displays. The study served as a simulator-based supplement to a concurrent on-road field study, allowing for controlled assessment of variables such as road curvature and object detection that were difficult to measure systematically in real-world conditions. The experimental design utilized a part-task driving simulator featuring a Kenworth truck cab mock-up and the STISIM simulation software. Fourteen male commercial driver license (CDL) holders participated, engaging in driving scenarios that varied by traffic density (high vs. low) and road curvature. Drivers performed three categories of secondary tasks: cellular phone dialing (auto-dial, local, long-distance), cognitive dialogue tasks (biographic questions or mental arithmetic), and visual/manual tasks involving a CRT text message display (reading messages, checking tachometer/time, tuning radio). Performance was measured through lanekeeping metrics (lane position, standard deviation, lane exceedence), vehicle speed, steering wheel rate, and object detection latency for pedestrians. Results indicated that driver-vehicle performance varied significantly depending on the type of secondary task. Visual tasks requiring reading from the CRT text message display had a more pronounced negative impact on driving performance than manual dialing or cognitive dialogue tasks. Specifically, lanekeeping stability and speed control were more degraded during text reading events. Performance was also affected by traffic density, though to a lesser extent than by task type. The study found that part-task simulators could replicate trends observed in field studies, suggesting their utility for ergonomic evaluation. The findings highlight that visual demand from in-cab displays poses a greater risk to heavy vehicle safety than manual or cognitive phone use, informing the development of workload assessment protocols for ITS devices.

Key finding

Reading text messages on a CRT display had a relatively more noticeable impact on driver-vehicle performance than either manual dialing or cognitive dialogue tasks.

Methodology

simulator

Sample size: 14

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

Ranked by relevance to this paper. Hover a topic for its definition.

• visual manual
• mobile phones
• mental demand
• manual
• workload measurement
• temporal

Information type

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• Empirical Findings: observational prevalence, behavioral performance data
• Methodological Resource: validation psychometrics